The present invention relates to a new and novel process for for the purification of pseudo-ionone and to a chemical complex formed during the process.
Pseudo-ionone is prepared from citral and acetone by the following reaction: ##STR1## This reaction is generally carried out at a temperature of between 0.degree. and 100.degree. C. During the reaction, a by-product, shown as formula (I) below, is formed at the same time as the pseudo-ionone, because of an impurity in the citral, thereby resulting in a mixture of pseudo-ionone and formula (I), referred to herein as a pseudo-ionone mixture or as crude pseudo-ionone. This by-product is the condensation product of isocitral and acetone, which is formed according to the following reaction: ##STR2## The by-product, i.e. condensation product formula (I), is more difficult to dehydrate than the aldol of citral, formed as an intermediate, which yields pseudo-ionone.
Moreover, condensation product formula (I) has a boiling point close to that of pseudo-ionone, and in order to separate these two compounds, it is necessary to use fractional distillation, which leads to a partial degradation of the pseudo-ionone. Accordingly, it would be desirable to provide a process of the preparation and isolation of pseudo-ionone wherein degradation of the pseudo-ionone is eliminated or substantially reduced.